The present invention relates to a photoresist top coat composition containing a particular fluorine-containing structure.
Fluorine-based compounds are developed or used in wide applied fields of advanced materials, due to characteristics such as water repellency, oil repellency, low water absorption, heat resistance, weatherability, corrosion resistance, transparency, photosensitivity, low refractive index, and low dielectric property. In particular, resist materials of fluorine-based compounds have recently and actively been studied as novel materials that are highly transparent to short wavelength ultraviolet rays such as F2 and ArF. A common molecular design in these applied fields is based on the achievement of various performances such as transparency at each used wavelength due to the introduction of fluorine, photosensitivity using acid characteristics of fluoroalcohols such as hexafluoroisopropanol (hexafluorocarbinol), adhesion to substrate, and high hardness, that is, glass transition point (Tg).
Recently, immersion lithography has rapidly emerged as a lithography for producing next-generation semiconductors. In particular, the entire business circle pays attention to it as a means for prolonging the lifetime of exposure technique by ArF excimer laser. In this case, liquid (e.g., water) is brought into contact with the photoresist surface. Therefore, how various problems, such as resist swelling, liquid penetration into the resist, and compound elution from the resist, are solved has become an important factor to improve the immersion lithography performance.
As a solving means, there is reported a process of coating the photoresist surface with a polymer protective film (see the following non-patent publication 1). For example, however, it becomes deficient in solubility in developing solution. Thus, it has not reached the level at which the material is optimized. This polymer protective film is a protective film to be coated on the photoresist film. Therefore, it is called a top coat or cover coat.
Non-patent publication 1: Mitsuru Sato, “TOK Resist & Material Development Status for Immersion Lithography”, [online], SEMATECH, LITHO FORUM 28-29 JANUARY 2004 LOS ANGELS, Calif., [Searched on Mar. 29, 2004], Internet <http://www.sematech.org/resources/litho/meetings/forum/20040128/presentations/06—193_Sato_TOK.pdf>
There is a demand for a measure to form a top coat by coating a resist film with a coating film, of which both exposed portion and non-exposed portion are dissolved in a developing solution in a short period of time at similar rates, to intercept water from the resist film. In this case, there has been a demand for a polymer compound that simultaneously satisfies performances such as less swelling in water, no corrosion of the photoresist of the underlayer, and the capability of adjusting refractive index of the film.